Plasma processing apparatus and plasma processing method

ABSTRACT

The present invention provides a plasma processing apparatus or a plasma processing method that can etch a multilayer film structure for constituting a gate structure with high accuracy and high efficiency. A plasma processing method of, on processing a sample on a sample stage  112  in a depressurized discharge room  117 , etching a multilayer film (including a high-k and a metal gate) at 0.1 Pa or less and with the sample stage  112  temperature-regulated by using a pressure gauge  133  to be used for pressure regulation and connected to the processing room and a main pump for exhaustion  130.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma processing apparatus or aplasma processing method for processing a semiconductor wafer 212 byusing plasma to form a wiring structure of a semiconductor device, andin particular, to the plasma processing apparatus or processing methodfor etching a film structure having films of multiple layers, i.e. filmsfor insulating upper and lower films for forming the wiring structureplaced on a surface of the semiconductor wafer 212 put on a sample stageplaced in a vacuum vessel which is rendered low-pressure.

2. Description of the Related Art

In recent years, there has been great progress in the trend towardhigher integration of semiconductor integrated circuit devices. As forMOS (Metal Oxide Semiconductor) type semiconductor devices, elementssuch as transistors are becoming miniaturized and higher-performance. Inparticular, a gate insulating film as one of the elements constituting aMOS structure is rapidly becoming thinner to cope with miniaturization,fast operation and lowered voltage of the transistors.

As for a material constituting the gate insulating film, a silicondioxide film (SiO2 film) has been conventionally used. On the otherhand, if the gate insulating film further becomes thinner in conjunctionwith miniaturization of gate electrodes, a tunneling current generatedby direct tunneling of carriers (electrons and holes) through the gateinsulating film, i.e. a gate leakage current increases. For instance, afilm thickness of the gate insulating film required by a device of a130-nm node is 2 nm or so in the case of the SiO2 film. However, thisarea is the area where the tunneling current starts to flow. Therefore,in the case where the SiO₂ film is used as the gate insulating film, thegate leakage current cannot be controlled so that power consumptionincreases.

Thus, a research is underway to use a material of higher permittivity asthe gate insulating film instead of the SiO2 film. As for an insulatingfilm of high permittivity (hereinafter referred to as a high-k film or ahi-k film), a TiO2 film, a Ta2O5 film and an Al2O5 film wereconventionally considered. Recently, an HfO2 film, an HfAlOx film, anHfSiOx film and the like are receiving attention because of excellentstability on silicon.

Conditions for processing such a high-k film are disclosed in JapanesePatent Laid-Open Publication No. 2005-45126 (Patent Document 1) forinstance. The conventional technology thereby disclosed specifies arange of gas composition and plasma density when etching a filmstructure composed of a resist pattern, an antireflection film, asilicon (polysilicon) film, a high-k film, an insulating film (SiO2film) and the like formed on a silicon substrate by using gasesincluding BC 13 and Ar so as to suppress side etching of the siliconfilm for a gate and improve accuracy of its shape.

In the case of the conventional technology, however, sufficientconsideration was not given to a condition for stably performing theprocessing and thereby improving reproducibility although it disclosedthe condition for improving controllability of the shape by etching amultilayer film including high-k. For instance, attention was notsufficient as to pressure in a processing room and a temperaturecondition of a sample, a sample stage and a member constituting theprocessing room when processing a substrate-like sample such as asemiconductor wafer 212 put on a platform in the processing room whichis placed in a vacuum vessel.

To be more specific, the temperature condition on the processing isstrict as to the film structure using the multilayer film for formingthe miniaturized wiring structure such as a high-k and metal gate film.Unless the processing is performed while precisely realizing these, anetching rate or accuracy of the shape becomes low so that processingefficiency and yield will be damaged. This is because these filmmaterials have lower reactivity than the silicon (polysilicon) filmwhich is a film for realizing a conventional gate structure. To improveprocessing speed by increasing the reactivity, it is inevitable toincrease the temperature on the surface of the sample being processed.

When the processing was performed by raising the temperature on thesurface of the sample, there was a problem that a photoresist film as amask placed over the film to be the film structure deteriorated bysoftening, deformation or the like so that functions as the mask loweredand the shape could not be realized with high accuracy. Furthermore,when high-frequency power supplied to the electrodes in the sample stagefor the sake of forming a bias potential is increased in order to raisethe temperature for the purposes of increasing the processing speed andimprove controllability of the shape, there was a problem that chargingdamage on the film structure increases during the processing or etchingof the upper mask increases.

Furthermore, when performing the processing as the film structureincluding the film composed of high-melting metal materials, reactionproducts including chemical compounds of these materials generated thenreattach to the surfaces of members constituting inner walls of theprocessing room and become accumulated in the case where the temperatureof the processing room is lower than the temperature of k and thesurface of the sample. As for the accumulated products, there is apossibility that they are peeled off by change of the temperature or aninteraction with plasma and attach to the surface of the sample to be aforeign substance. Therefore, it becomes necessary to suppress theattachment of the products. To be more specific, it is necessary toraise the temperature of the inner walls of the processing room to behigher than the temperature of the sample stage. In the case ofperforming the processing at high temperature to improve the efficiencyas described above, however, it requires a structure for further raisingthe temperature of the inner walls of the processing room so that thestructure of the processing device becomes larger and more complicated,resulting in higher manufacturing costs. In the case where an outersurface of the vacuum vessel exceeded 50° C., there was a problem thatit required facilities for safety as well as installation of a heatinsulating material therefor so that extra facilities are required andinstallation space is required, leading to increased installation costs.

An object of the preset invention is to provide a plasma processingapparatus or a plasma processing method that can etch a multilayer filmstructure for constituting the gate structure with high accuracy andhigh efficiency or to provide a plasma processing apparatus of a simpleconfiguration at low cost.

SUMMARY OF THE INVENTION

The object is achieved by (same as what is claimed is).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an overview of a configuration of anembodiment related to a plasma processing apparatus of the presentinvention;

FIG. 2 is a schematic diagram showing an enlarged configuration of aperiphery of a sample stage of the embodiment shown in FIG. 1;

FIG. 3 are schematic diagrams of a film structure for realizing a wiringstructure of a semiconductor device which is a subject of the embodimentshown in FIG. 1;

FIG. 4 are schematic diagrams of the film structure for realizing thewiring structure of the semiconductor device which is the subject of theembodiment shown in FIG. 1; and

FIG. 5 is a graph showing a condition in the case of processing the filmstructure shown in FIG. 3 or FIG. 4 on the plasma processing apparatusaccording to the embodiment shown in FIG. 1, which shows the effects ofchange in processing temperature against change in pressure in theprocessing room.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereunder, embodiments of the preset invention will be described byusing the drawings.

First Embodiment

A processing chamber of this embodiment will be described by usingFIG. 1. FIG. 1 is a longitudinal section showing an overview of aconfiguration of the embodiment related to a plasma processing apparatusof the present invention.

In FIG. 1, a plasma processing apparatus 100 includes a vacuum vessel101, electromagnetic wave supply means provided in an upper part thereofand evacuation means 107 placed in a lower part of the vacuum vessel101. Furthermore, the vacuum vessel 101 has a processing room placedtherein, which is approximately cylindrical space for processing aprocessing subject sample inside it and has its side wall portion as anapproximately rectangular plane coupled with a vacuum transportcontainer 104 for transporting a sample in depressurized internal space.

The processing room in the vacuum vessel 101 is connected to a transportroom placed inside the vacuum transport container 104, and is opened andblocked during or after the processing by opening and closing meansdescribed later. To be more specific, they are communicated or blockedoff by an air gate valve 111 which opens and closes and is placedbetween them. With the gate valve 111 opened, the space inside thetransport room and the space inside the processing room communicate sothat their pressures become approximately equal. When the gate valve 111is open, a wafer as a sample is transported on a sample stage 112 placedin the processing room from inside the transport room and mountedthereon.

The electromagnetic wave supply means provided in the upper part of thevacuum vessel 101 includes means for generating a radio wave of apredetermined frequency and supplying an electric field in theprocessing room and means composed of a solenoid coil 103 and the likeand generating a magnetic field and supplying a magnetic field. Themeans for supplying an electric field of this embodiment has a waveguide113 placed above a member constituting a ceiling plane of the vacuumvessel 101 and a magnetron 114 for plasma excitation installed at an endof the waveguide 113, where a microwave is generated by the magnetron114 and led in the waveguide 113 toward the processing room.Furthermore, a ceiling member of the processing room which is a lowerend of the waveguide 113 includes a plate 115 composed of a dielectricsuch as quartz for conducting a transmitted microwave to the inside ofthe processing room below and a shower plate 116 placed below the quartzplate and having multiple holes formed thereon for dispersedlyintroducing a supplied process gas for processing inside the processingroom.

The space formed below the shower plate 116 and above the sample stage112 is a discharge room 117 in which plasma is formed by an interactionbetween the radio wave introduced to the supplied process gas throughthe quartz plate 115 and the magnetic field supplied from a magneticfield generating portion. Furthermore, space is formed between thequartz plate 115 and the shower plate 116 with a minute clearance. Theprocess gas to be supplied to the discharge room 117 is supplied firstto this space, and flows into the discharge room 117 through the aboveholes penetrating the shower plate 116 and communicating this space withthe discharge room 117. The space is a buffer room 118 provided so thatthe process gas dispersedly flows into the discharge room 117 frommultiple holes. The process gas is supplied from a controller 121 foradjusting supply of fluids such as a gas to the processing chamber via aprocess gas line 119 and a process gas cutoff valve 120.

Thus, the process gas is dispersedly introduced into the discharge room117 from multiple holes, and the holes are mainly placed at positionsopposed to the position at which the sample is placed on the samplestage 112 so as to uniform plasma density in conjunction with a functionof the buffer room 118 capable of dispersing the gas to be more uniform.A lower ring 122 is placed on a peripheral side of the quartz plate 115and the shower plate 116. Inside the lower ring 122, there is a gaspassage communicated with the gas line 119 through which the process gasflows to the buffer room 118.

Furthermore, below the shower plate 116, a discharge room outer wallmember 123 and an inner wall member 124 are placed forming the dischargeroom 117 by facing the plasma inside the vacuum vessel and in contactwith the lower ring 122 and the shower plate 116 on their undersides.The inner wall member 124 and the outer wall member 123 are each in anapproximately cylindrical shape and almost concentrically configured inthis embodiment. The outer wall member 123 is placed with a heater 134wound around its peripheral surface, where the temperature of the outerwall member 123 is regulated so as to regulate surface temperature ofthe inner wall member 124 having contacted it.

The outer wall member 123 has a discharge room base plate 125 placed onits peripheral side in contact with its underside. The underside of thedischarge room base plate 125 is in contact with a vacuum chamberportion placed below it. The inner wall member 124 is a member foracting as a ground electrode to the plasma inside the discharge room 117and the sample stage 112 which plays a role of an electrode, and hasnecessary area for stabilizing a plasma potential. It is necessary, forthe sake of the action as the ground electrode, to sufficiently secureheat conduction as well as conductivity between the inner wall member124 and the outer wall member 123 or the lower ring 122 to be in contactand in connection with.

According to this embodiment, the surface temperature of the wallsconstituting the vacuum chamber is regulated so as to adjust theinteraction among their surfaces, plasma and particles, gases and aresidue included therein. And their temperature is kept higher than thetemperature of the sample stage. It is possible to put plasmacharacteristics such as plasma density and composition in a desiredstate by thus adequately adjusting the interaction between the plasmaand the walls of the vacuum chamber facing it.

Below the discharge room base plate 125, the processing chamber isformed by placing a lower case wall 15 constituting the lower part ofthe vacuum vessel, a bottom case wall 16 connected thereto from belowand constituting the bottom of the vacuum vessel, an internal lowerchamber 128, an internal chamber 126 placed therein and coupled with thedischarge room base plate 125 with its top surface in contact with theunderside of the discharge room base plate 125, and an electrode base127 as multiple beams for connecting with the lower part of the internalchamber 126 and supporting the sample stage 112 in the space in theprocessing room.

An evacuation device 107 for adjusting exhaustion inside the vacuumvessel is placed in the lower part of the bottom case wall 16. In thisembodiment, the evacuation device 107 is provided with a flow regulatingvalve 129 placed at the center of the internal lower chamber 128 and thebottom case wall 16 to adjust cross-section area of an opening forexhausting the gas in the processing room and thereby adjust an amountand speed of the exhaustion with multiple rotating plate-like flapsplaced in a passage below and communicated with the opening, anexhaustion line communicated with an exit of the passage and composed ofa main pump 130 such as a turbo-molecular pump for exhausting the gas inthe processing room, and a valve plate 131 placed in the processing roomand blocking off the lower part of the opening.

A piping 132 connected to the processing room is provided with apressure gauge 133 to be used for pressure regulation of the processingroom. As for the main pump 130 and pressure gauge 133, those capable ofachieving 0.1 Pa or less are selected.

FIG. 2 shows details of the periphery of the sample stage 112. FIG. 2 isa longitudinal section showing an enlarged overview as to aconfiguration of the periphery of the sample stage in the embodimentshown in FIG. 1. Inside a bottom electrode 211 composed of a conductivemember placed inside the sample stage 112, there is provided a groove213 for circulating a refrigerant for the purpose of temperatureregulation of a semiconductor wafer 212 as a processing subject to beprocessed by the plasma formed in the discharge room 117. The groove 213for the refrigerant is connected with a circulation temperatureregulator 217 for temperature regulation via a flexible tube 218 forconnection. The circulation temperature regulator 217 has a temperatureregulating portion 219 composed of a heat exchanger and a refrigeratorfor temperature regulation and a circulating pump 220 built therein.

A dielectric film 214 for electrostatic absorption is provided on a topsurface of the sample stage 112, which causes the semiconductor wafer212 to be electrostatically absorbed to the bottom electrode 211 byusing an electrostatic absorption direct-current power source 215connected to the bottom electrode 211 so as to perform the temperatureregulation. A high-frequency power source 216 for exerting reactioncontrol over an etching material on the surface of the semiconductorwafer 212 is connected in parallel with the electrostatic absorptiondirect-current power source 215. A cover 221 is provided on the top sidesurface in order to protect the surface of the bottom electrode 211other than the semiconductor wafer 212.

The semiconductor wafer 212 as a processing subject sample transportedinside the transport room of the depressurized vacuum transportcontainer 104 by a robotic arm in the transport room is delivered on thesample stage 112 and is put on the top surface of the sample stage 112in the processing room depressurized equally to the inside of thetransport room by operation of the evacuation device 107. Thesemiconductor wafer 212 put thereon is put on the dielectric film 214and absorptively retained on the top surface of the dielectric film 214by the electrode in the dielectric film 214 to which power from theelectrostatic absorption direct-current power source 215 is supplied.

As for the process gas introduced into the discharge room 117 in thisstate, an interaction arises between an electric field due to amicrowave propagated by transmitting through the quartz plate 115 andthe shower plate 116 and the magnetic field supplied from the solenoidcoil 103 to excite the process gas so that the plasma is generated inthe discharge room 117. The semiconductor wafer 212 on the sample stage112 is processed by using the plasma. High-frequency power of apredetermined frequency is supplied from the high-frequency power source216 to the bottom electrode 211 composed of the conductive member placedinside the sample stage 112 during the processing. And a desired biaspotential is generated on the surface of the semiconductor wafer 212,and charged particles in the plasma are attracted to the surface of thesemiconductor wafer 212 so as to promote the processing and realize adesired processed shape.

During the processing, the inner wall member 124 of the discharge room117 is maintained at predetermined temperature by the heater 134. Theevacuation device 107 is in operation even during the processing, andmaintains the inside of the processing room at a predetermined pressurevalue by discharging the supplied process gas and plasma out of theprocessing room together with the products generated in conjunction withthe processing.

FIG. 3 show a film structure as a wiring structure for the semiconductordevice which is a subject of the plasma processing of the presentinvention. FIG. 3A is a schematic diagram showing an unprocessed stateof the film structure formed on the surface of the semiconductor wafer212 as the processing subject. In FIG. 3A, the film structure has asilicon substrate 311 as a lower base, and a high-k film 312 and a gatefilm 313 to be a gate of the semiconductor device placed in this orderover it, and a patterned oxide film 314 to be a mask further over them.Here, the gate film 313 is composed of a simple or a compound filmcomposed of high-melting metal materials such as Ti, Ni, Mo, Ru, Hf, Ta,W, Re, Ir, Pt, La, Eu and Yb.

Furthermore, a photoresist 315 composed of an organic material such as aresin to be the mask on processing the oxide film 314 may be placed overthem. FIG. 4 show the case where the material of the patterned film 315to be the mask is a resist mask.

In the case of such a film structure, after the oxide film 314 is etchedwith the photoresist 315 as the mask, the gate film 313 and high-k film312 placed further underneath are etched with the shape of the processedoxide film 314 as the mask. The shapes after the processing are shown inFIG. 3B and FIG. 4B respectively.

FIG. 5 is a graph showing a condition in the case of processing the filmstructure shown in FIG. 3 or FIG. 4 on the plasma processing apparatusshown in FIG. 1, which shows the effects of change in processingtemperature against change in pressure in the processing room. FIG. 5shows (1) the case where an HBr gas reacts when a gate member is Ta, (2)the case where a Cl₂ gas reacts when the gate member is Hf, (3) the casewhere the HBr gas reacts when the gate member is Hf, and (4) the casewhere the HBr gas reacts when the gate member is TaC.

As shown in FIG. 5, in all the cases of (1) to (4), there is a drasticchange in the temperature of the sample volatilized by the materialconstituting the film when the pressure in the processing room is 0.1 Paor less. To be more specific, lower limit temperature of a samplesurface capable of volatilizing the products at a predetermined ratio is0.1 Pa or less. In particular, it drastically drops at the pressure of0.06 Pa or less. Especially, it drastically changes to 60° C. or less inthe cases of (1), (2) and (4).

If the temperature of the semiconductor wafer 212, i.e. the temperatureof the bottom electrode exceeds 60° C. in the case where the bottomelectrode base material 211 is aluminum and the dielectric film 214 isalumina, a linear expansion coefficient of aluminum is 2.3×10⁻⁵ (1/° C.)while a linear expansion coefficient of alumina is 7.1×10⁻⁶ (1/° C.) sothat a dimension difference of approximately 0.2 mm arises whenelectrode temperature is 65° C. and a temperature difference is 45° C.To acquire stress based on this, it is 1×10⁵ g/mm², which exceedsallowable stress 5×10⁴ g/mm and causes damage. Thus, use in excess of60° C. requires a structural change such as change of the material for amechanical reason. As a material of a low linear expansion coefficientdeteriorates thermal responsiveness, there arises a temperature rise dueto plasma heat input.

In the case of performing the processing with the sample surface at 60°C. or more, deterioration of the resist mask becomes so significant thatprocessing accuracy lowers as to the shape of the lower film using it asthe mask. In the case of a photoresist composed of a hydrocarbonmaterial in particular, deformation and softening thereof becomessignificant. And if the power of the bias supplied to the electrode ofthe sample stage is increased to raise the temperature, selectivitybetween the resist and the lower film lowers so that side etchingincreases and the processing accuracy is reduced.

Thus, this embodiment processes the sample by maintaining the inside ofthe processing room at the pressure of 0.1 Pa or less or preferably 0.06Pa or less so as to realize the condition of the processing forsuppressing the problem. To be more specific, it is possible, by settingthe sample surface at 60° C. or less while maintaining the pressurecondition, to perform the processing with improved reactivity of thefilm material and at improved processing speed. In addition, it ispossible to suppress the deterioration of the resist mask so as tobalance the above with improvement in the processing accuracy.

As for the range of such a condition, the lower limit of pressure is0.025 Pa or preferably 0.03 Pa in view of exhaustion efficiency, and thelower limit of temperature for achieving a predetermined volatilizationvolume in this case is 45° C. The action and effects can be exerted byperforming the processing in an area of 60° C. or less above a linesegment connecting a point of 0.025 Pa, 45° C. with a point of 0.1 Pa,60° C. in FIG. 5.

To be more precise, the range of a suitable condition for the processingis the range of T=60° C. or less above the line at which a temperature Tof the sample or the sample stage 112 is per following (1). Thisembodiment can increase flexibility in selection and setup of recipes ofsample processing by expanding the range of the pressure and temperaturecapable of realizing such a processing condition.

T=200P+40  (1)

T: temperature (° C.)

P: pressure (Pa)

Furthermore, according to this embodiment, the temperature of themembers facing the plasma in the processing room such as the inner wallmember 124 and the internal chamber 126 of the discharge room ismaintained by keeping the temperature of the sample stage 112 or thesample high so as to perform the processing. In this case, as shown inFIG. 5, the pressure in the processing room is kept at 0.1 Pa or less toincrease volatility of the reaction products generated in the processingroom, which suppresses the reattachment of the products to the surfacesin the processing room and generation of foreign substances due todeposition thereof.

The temperature of the members placed in the processing room and facingthe plasma is regulated to be equal to or higher than the temperature ofthe surface facing the plasma of the sample in process put on the samplestage so as to prevent the products generated in conjunction with theprocessing from attaching to the surface of the members in theprocessing room and accumulating thereon. According to this embodiment,the heater 134 is placed, which is mounted covering and contacting thecircumference of a lateral wall surface of the discharge room outer wallmember 123 in order to regulate the temperature of such members in theprocessing room. The heat generated by the operation of the heater 134is transmitted to the inside of the processing room to adjust thetemperature of the surface of the member in the processing room such asthe inner wall member 124 to be higher than the surface of thesemiconductor wafer 212 which is the sample.

In this case, if the temperature of the sample surface is exceeding hightemperature such as 60° C., it is necessary to set the temperature ofthe inner wall member 124 in the processing room at this or highertemperature so that the temperature of the heater 134 becomes evenhigher. Thus, it requires means for securing safety, for instance, bycovering the processing room outer wall surface with a heat insulatingmember or the like so that there is little danger even if a user or aworker touches this heated portion. Therefore, the structure becomesfurther complicated, and space for installation thereof is alsonecessary, resulting in increased costs for installation and operation.

According to this embodiment, the processing device sets the temperatureof the sample in process at 60° C. or preferably 50° C. or less andperforms the processing by regulating the temperature of the inner wallsof the processing room to be higher than this so as to lower operatingtemperature of a heating device compared with the conventional deviceand eliminate necessity of the heat insulating member or the like of theprocessing room. In this case, it is possible, by reducing the pressureof the sample in process to 0.1 Pa or less or preferably 0.06 Pa, ormore preferably 0.05 Pa or less, to process the sample surface inprocess at the above temperature or less when processing the filmstructure including the film composed of high-melting metal materialsshown in FIG. 3. Thus, it is possible to reduce generation of foreignsubstances during the processing and suppress the yield by using theprocessing device of a simpler structure.

To realize the low pressure of 0.1 Pa or less, the distance fromdischarge space on the wafer to the pump for exhaustion must beminimized in order to enhance the conductance thereof. In this case, itis best to put the bottom electrode at the center of the chamber as inFIG. 1. It is desirable, however, to set the electrode temperature at60° C. or less also in view of allowable temperature limit of a cylinderand a sensor used for a boosting mechanism for transport which is notshown.

As in the drawings, in the case of processing Hf, a conventional devicewas capable of the processing at low temperature by using HBr as etchinggas. It becomes possible, by rendering the pressure low, to performetching with the C12 gas at 60° C. or less. Thus, the range of choice ofthe gases for etching is expanded, and it becomes possible to variouslycontrol other processed shapes.

1. A plasma processing method of placing a sample having a layer of ahigh-melting metal film on a surface thereof in a vacuum vessel andprocessing it by forming plasma in the vacuum vessel, wherein: thesample is processed on condition that temperature of the sample is abovea line connecting 60° C. as temperature and 0.1 Pa as pressure in thevacuum vessel with 30° C. as temperature and 0.01 Pa as pressure in thevacuum vessel.
 2. The plasma processing method according to claim 1,wherein a film underneath the high-melting metal film is a film of ahi-k material including Hf.
 3. The plasma processing method according toclaim 1 or 2, wherein the high-melting metal film is composed of asimple substance or a compound or a chemical compound of multiplesubstances out of Ti, Ni, Mo, Ru, Hf, Ta, W, Re, Ri, Pt, La, Eu and Yb.4. The plasma processing method according to claim 1 or 2, wherein: thesample is put on an insulating film composed of ceramics of a samplestage placed in the vacuum vessel and including a base material made ofaluminum or an alloy thereof and the insulating film placed on a surfacethereof; and temperature of the sample is regulated to 60° C. or less bytemperature regulating means placed in the base material.
 5. The plasmaprocessing method according to claim 3, wherein: the sample is put on aninsulating film composed of ceramics of a sample stage placed in thevacuum vessel and including a base material made of aluminum or an alloythereof and the insulating film placed on a surface thereof; andtemperature of the sample is regulated to 60° C. or less by temperatureregulating means placed in the base material.
 6. The plasma processingmethod according to claim 3, wherein Cl or HBr is supplied into thevacuum vessel and a film for a gate is etched to form a gate structure.7. A plasma processing apparatus comprising: a processing room placed ina vacuum vessel to have plasma formed inside it; a sample stage placedin a lower part of the processing room to have a sample having a layerof a high-melting metal film on the surface as a processing subject bythe plasma placed on a top surface thereof; a heater which heats thesurface of a member of the processing room facing the plasma atprocessing temperature of the sample or higher temperature, wherein: theplasma is formed in the vacuum vessel and the sample is processed oncondition that pressure in the processing room is 0.1 Pa or less.
 8. Theplasma processing apparatus according to claim 7, wherein a filmunderneath the high-melting metal film is a film of a hi-k materialincluding Hf.
 9. The plasma processing apparatus according to claim 7 or8, wherein the high-melting metal film is composed of a simple substanceor a compound or a chemical compound of multiple substances out of Ti,Ni, Mo, Ru, Hf, Ta, W, Re, Ri, Pt, La, Eu and Yb.
 10. The plasmaprocessing apparatus according to claim 7 or 8, wherein: the sample isput on an insulating film composed of ceramics of a sample stage placedin the vacuum vessel and including a base material made of aluminum oran alloy thereof and the insulating film placed on a surface thereof;and temperature of the sample is regulated to 60° C. or less bytemperature regulating means placed in the base material.
 11. The plasmaprocessing apparatus according to claim 9, wherein: the sample is put onan insulating film composed of ceramics of a sample stage placed in thevacuum vessel and including a base material made of aluminum or an alloythereof and the insulating film placed on a surface thereof; andtemperature of the sample is regulated to 60° C. or less by temperatureregulating means placed in the base material.
 12. The plasma processingapparatus according to claim 9, wherein Cl or HBr is supplied into thevacuum vessel and the film for a gate is etched to form the gatestructure.